The present disclosure relates to methods for improving the purity and quantity of materials, including synthetic materials, recovered from recycling disposable absorbent articles. More specifically, the present disclosure relates to methods for easily and economically separating the materials in a disposable absorbent article, removing fluid absorbed by superabsorbent polymers (SAP), and recovering the constituent materials such as polymer, cellulosic fibers, and superabsorbent polymer.
There has been an increasing use of disposable absorbent articles including diapers each year. Currently, all the used disposable absorbent articles are incinerated or disposed in a landfill. However, incinerating or disposing the articles in a landfill can result in the problems of lack of landfill sites or problems due to incineration that results in high processing cost and adversely affects the environment due to carbon dioxide produced during the process.
Further, because large quantities of materials (resources) are consumed for manufacturing disposable absorbent articles relative to the purpose of treating human waste, there has been an increasing demand for recycling or reusing disposable absorbent articles. Thus, there is a need for efficient and economical processes for recycling used disposable absorbent articles into individual constituents by decomposing or isolating main constituents of the absorbent articles without harming the environment. In general, disposable absorbent articles, such as baby diapers, consist of polypropylene (PP), polyethylene (PE), superabsorbent polymer (SAP), cellulose pulp, and the like.
Previous attempts involved the use of harmful chemicals, and resulted in the disposal of useful materials due to inefficient recovery techniques. It is particularly difficult to separate cellulosic fibers from polymers layers due to the use of adhesives. It is also difficult to process absorbent material that has been prepared by mechanically mixing superabsorbent polymers and cellulose pulp in a uniform distribution having a certain arrangement. Such material cannot be isolated into individual materials mechanically or by other physical measures, because superabsorbent polymers become a gel state as they absorb moisture from human waste to be swollen (i.e., become larger in volume) and are tangled with cellulose pulp fibers.